# What is the implicit derivative of 25=cosy/x-x?

Nov 22, 2015

Remember to use the chain rule when differentiating the y-variable ...

#### Explanation:

Taking the derivative:

$0 = \frac{\left(x\right) \left(- \sin y\right) \left(y '\right) - \left(\cos y\right) \left(1\right)}{x} ^ 2 - 1$

Now, solve for $y '$

$y ' = - \frac{{x}^{2} + \cos y}{x \sin y}$

hope that helped